Carburetor



Se t. 19, 1933. w. E. ARMSTRONG 1,927,302

CARBURETOR Filed June so. 1930 5 Sheets-Shet 1 1k ATTORNEYS w. E. ARMSTRONG 1,927,302

CARBURETOR Filed June 30, 1930 3 Sheets-Sheet 2 1 N VEN TOR.

A TTORNEYJ".

Sept. 19, 1933. w ARMSTRONG 1,927,302

CARBURE'IOR Filed June 50, 1930 3 Sheets-Sheet 3 Ewan:

ITITFIW I|l|llllllllllllllllllll will illlli I N VEN TOR.

A TTORNEYS Patented Sept. 19, 1933 "UNITED STATES PATENT OFFICE 1,927,302 CARBURETOR I Werner E. Armstrong, Milwaukee, Wis.

Application June 30, 1930. Serial No. 464,915

' 20 Claims.

' This invention relates to improvements in carburetors.

To obtain proper carburetion under all driving and throttling conditions has presented a problem which has heretofore been unsolved. In the small to create enough pull to raise fuel'at low volumes, and it must be sufiiciently large to permit passage of air at large volumes without undue restriction. Thus the venturi of the ordinary carburetor must be a compromise between the two extremes and is, therefore, ideal at only one volume. To endeavor to overcome this difficulty, some carburetors with a fixed venturi have been constructed to embody auxiliary air valves which are brought into use when a greater volume of air is demanded than can be supplied through the fixed venturi opening. Other carburetors have utilized other forms of compensators to endeavor to remedy conditions at volumes both above and below the normal volume possible with the fixed venturi. These devices, while undoubtedly improving conditions to a certain extent, still fail to provide a suitable mixture under all speeds and loads, and cause undesirable fiat spots in the carburetion.

it is, therefore, one of the objects of this invention to provide an improved carburetor which is so constructed as to maintain a proper mixture of air and fuel under all conditions.

A further object of this invention is to provide a carburetor in which a variable venturi is utilized to accomplish the above mentioned object.

A further object is to provide .a carburetor of ulated venturi, a lower partial vacuum at the fuel jet for all volumes below maximum .without affecting the power, a lower partial vacuum at the fuel jet at and above maximum volumes to increase the efliciency and economy of operation,

ideal fuel jet position with respect'to the Venturi opening, simplicity of construction-and operation, and economy of manufacture.

',With the above and other objects in view, the

invention consists of the improved carburetor and all its parts and combinations, as set forth in the claims, and all equivalents thereof.

In the accompanying drawings, illustrating one complete embodiment of the preferred form of the invention, in which the same reference numerals designate the same parts in all of the views:

Fig. 1 is a sectional view of the improved carburetor takerron line 11 of Fig. 2;

Fig. 2 is a sectional view taken on line 22 of Fig; 1; I

Fig. 3 is an end view of the device;

Fig. 4 is a sectional view taken on line 4-4' of Fig. 1;

Fig. 5 is an enlarged detail plan view showing the Venturi construction, with the venturi at a minimum adj ustment;

. Fig. 9- is a fragmentary sectional view of a carburetor casing showing a modified form of 7 construction; and

Fig. 10 is a similar view showing an additional modification.

Referring to the drawings the numeral 10 designates a cup-shaped casing portion forming a fioat chamber, said portion having an inner wall 11 of considerable thickness, supporting a.

side plate 1-2. A cover 13 for thefioat chamber is provided with a fuel inletopening 14. The

cover is also equipped with valve mechanism 15 which is controlled by a float 16 in the conventional manner, to maintain a desired level of fluid within the chamber. Fuel ducts 1'7 and 18 extend from the float chamber to valve chambers 19 and 20 respectively within the wall portion 11 (see Fig. 4). An L-shaped duct 21 extends from the valve chamber 19-into a lateral extension 22 of the plate 12. Another duct 23 connects the valve chamber 20 with the duct 21. A needle valve member, or idling pin 24, which is adjustably mounted in the usual manner controls the flow of fuel-from the valve chamber 19 to the duct 21. A slidably mounted metering pin controls the flow from the chamber 20 to the ducts 23 and 21. A fuel feed jet 26, which extends upwardly from the extension 22 of the plate 12, communicates through a passageway 27 with the fuel duct 21.

A peripheral wall 28 of the main casing has one edge secured-to the plate 12 by bolts29. An outer plate 30 having a cylindrical air intake portion 31 extending therefrom is secured to the other edge of the peripheral wall by bolts 32. A tubular member 33 is connected by bolts 34. which extend through a lower flange 35 thereof to the upper portionof theperipheral wall. 28. Said portion of the wall 28.is formed with an opening 36 which registers with the bore of the tubular member 33. An upper flange 37 ,is formed on the tubular member to facilitate connection of the latter with the intake manifold of a combustion engine.

A butterflyovalve 38, mounted in the usual manner in the air intake cylinder 31, is arranged for connection with a choke control. Another butterfly valve 39 is mounted on a rod 40, the latter being journaled through the tubular portion 33. A lever 41, secured to one end of the rod 40, is adapted to be connected to a throttle lever-in the usual manner. A cam 42 is also rigidly mounted on the rod adjacent the lever 41. Y

A'pin 43 extending from the casing has a bracket 44 loosely mounted thereon (see Fig. 4),

said bracket having an arm 45 extending there-' from and engaging beneath the cam 42. A coil spring 46, surrounding the'pin 43 has one end secured to the bracket 44 and its other end to the casing. Another arm 47, extending from the bracket 44 has its outer end pivotally connected to the metering pin 25. Thus, upon movement of the lever. 41 to open the valve 40, the cam 42 ltl-ie metering pin, the latter will be moved to increase the flow of fuel from the valve chamber 20, through the ducts 23 and 21 to the fuel jet Shafts 48 which are journaled in an intermed'i ate position between the casing plates 12 and 30 "have the novel Venturi rollers 49 rigidly mounted thereon, the shafts being so positioned with relation to one another that the rollers engage one another as shown in the drawings. The shafts 48 project through the plate 30 and a band spring 50 has one end secured to the end of one of the shafts 48 and its other end to the casing. Al-

though this is the preferred manner of applying" tension means to the rollers, any other suitable arrangement may be employed.

The Venturi rollers 49 arepreferably arranged to rotate together by means of intermeshing gears 51 rigidly mounted or formed on adjacent ends pf the rollers. ,1

Each Venturi roller has its peripheral surface formed with a recess 52 of substantially V-shape,

the said recess increasing in depth as the width increases. The recess is'further so shapedthat it presents a substantially true semi-circle at all positions of rotation of the roller, said semicircle increasing in size as the rolleris turned.

A Thus, with the two Venturi rollers properly positioned with relation to one another and gea d.

together, there is formed between the two rollers (as shown in Figs. 5, 6 and 7) a substantially true circular opening of varying size which surrounds the upper end portion of the feed pipe 26. Fur thermore, the feed pipe is concentrically positioned in the recess so that there is an air passageway of substantially the same size on all sides of the feed pipe opening.

Each Venturi roller is provided with a laterally extending arm, vane or piston 53 which is of substantially the same width as the distance between'the casing plates 12 and 30. The inner surface of the peripheral wall 28 of the casing is curved as at 54 to-conform to the arc of movement of the ends of the pistons 53.

The upper'portion of the casing is separated from the lower portion thereof by partitions 55 which extend from the peripheral wall to the sides of the rollers to form with the pistons a dash-pot construction, there being a slight clearance between the ends of said partitions and the rollers.- This defines an upper mixing chamber 56 and a lower chamber-57. Other partitions 58 within the chamber 56 extend downwardly from the opening 36 in the peripheral wall to within a short distance from the top of the rollers. While these latter partitions are not essential, they aid in directing the mixture of air and fuel to the tubular portion 33.

In operation, the idling pin 24 is first adjusted to allow a sufficient quantitymf fuel to pass into theduct 21. Next, the throttle valve 39 is opened. Air will then be drawn from the upper chamber 56 and from the portions of said chamber directly above the pistons 53 producing a pressure lower than atmospheric pressure within said chamber. This causes air from the outside which entersthe lower chamber 57 through the cylinder 31, to pass at a relatively high speed through the Venturi opening which is of the minimum size shown in Fig. 5, and around the fuel jet 26. This action causes fuel to bedrawn from the jet and to be mixed with the incoming air. As air is-drawn from the upper chamber, the efl'ect is also to raise or rotate the pistons 53, as shown by the dotted lines in Fig. 2. The amount of movement of the pistons is in direct proportion tothe diiference in air pressure in the upper and lower chambers 56 and 57. As thepistons are raised, the Venturi rollers 49 are rotated against the tension of the spring 50 to increase the size of the air opening surrounding the fuel, jet. The tension of the spring is such that a proper balance ismaintained between the fuel discharged from the jet and the an; admitted through the Venturi opening. With operated through the cam 42 on the throttle shaft,

has been provided. Thus, when the throttle is opened further additional fuel will be fed to the jet 26 to compensate for the additional air admitted-by the enlarged 'Venturi opening. The use of a metering pin, however, is not essential, as the increasing volume of air admitted through balance air and fuel admission from the minithe Venturi opening will act to draw proportion ately greater charges of fuel from the jet 26.

Thus, with the improved carburetor, embodying the novel variable venturi, it is possible to mum established by throttle idling position to whatever maximum the motor is able to produce, with an unbroken column of correctly carbureted air. Maximum economy and performance is established under these conditions, as a lower pressure or higher vacuum is possible at part throttle at the jet, and a maximum efficiency is brought about at full volumes due tothe enlarging of the venturi, and the consequent freer passage-of air, the suction being limited only to a degree sufficient to draw fuel from the jet in a proper pro portion.

In the preferred'form of the invention illustrated, two Venturi rollers are utilized so as to have a circular opening surrounding the fuel jet. It is practical. however, to use one venturi only, as shown in Fig. 10, having it rotate adjacent a wall or partition, with the fuel jet in the opening between the roller and the wall. It is also possible to utilize two Venturi rollers-with one rotating adjacent a wall of the casing, and with the other roller only carrying the piston, as shown in Fig. 9. Other changes are also possible in the details of construction without departing from the spirit of the invention, and it is therefore to* be understood that all changes and modifications are included as may come within the scope of the claims. a,

What I claim is:

1. In a carburetor having an air inlet cham-.

ber, a mixing chamber provided with an arcshaped wall, and a fuel jet, a variable expanding venturi for regulating the admission of air to said mixing chamber, said venturi embodying a rotatable member having its outer surface formed with a recess'of gradually increasing size in the direction of flow forming a variable opening between the air inlet chamber and the mixing chamber, the upper portion of the fuel jet being positioned within said opening, and a piston carried by said rotatable member with its end movable adjacent the arc-shaped wall of the mixing chamber, said piston being movable in response to air pressure differences in the mixing chamber and air inlet chamber to automatically control the rotatable member.

2. In a carburetor having an air inlet chambet, a mixing chamber provided with an arcshaped wall, and a fuel jet, a variable expanding venturi for regulating the admission of air to said-mixing chamber, said ve nturi embodying a rotatable member having its outer surface formed with a recess of gradually increasing size in the direction of flow forming a variable opening between the air inlet chamber and the mixing chamber, the upper portion of the fuel jet being positioned within said opening, a piston carried by said rotatable member with its endmovable adjacent the arc-shaped wall of the mixing chamber, said piston being movable in response to air pressure differences in the mixing chamber and air inlet chamber to automatically control the rotatable member, and tension means for resisting movement of said piston.

3. In a carburetor having an air inlet chamber, a mixing chamber provided with opposite areshaped walls, and a fuel jet, a variable venturi for regulating the admission of air to said mixing chamber, said venturi embodying a pair of rotatable members positioned adjacent one another and having their outer surfaces formed with registering recesses of gradually increasing size forming a variable opening between the air inlet chamber and the mixing chamber, the upper portion of the fuel jet being positioned within;

said opening, and a piston carried by each rotatable member with its end movable adjacent an arc-shaped wall of the mixing chamber, said pistons being movable in response to air pressure differences in the mixing chamber and air inlet .chamber to automatically control the rotatable members. I

4. In a carburetor having an air inlet chamber, a mixing,chamber provided with opposite arc-shaped walls, and a fuel jet, a variable venturi for regulating the admission of air to said mixing chamber, said venturi embodying a pair .of rotatable members geared to one another and having their outer surfaces formed with registering recesses of gradually increasing size forming a variable opening between the air inlet chamber and the mixing chamber, the upper portion of the fuel jet being positioned within said opening, and .a piston carried by each rotatable member with its end movable adjacent an arc-shaped wall of the'mixing chamber, said pistons being movable in response to air pressure differences in the mixing chamber and air inlet chamber to automatically control the rotatable members.

5. In a carburetor having an air inlet chamber, a mixing chamber provided with an arc-shaped wall, and a fuel jet, a variable venturi for regulating the admission of air to said mixing chamber, said venturi embodying a rotatably mounted member having its outer surface formed with a recess of gradually increasing size forming a variable opening between the air inlet chamber and the mixing chamber, the upper portion of the fuel jet being positioned within said opening, a piston carried by said member with its end movable adjacent the arc-shaped wall of the mixing chamber, said piston being movable in response to air pressure differences in the mixing chamber and air inlet chamber to automatically control the member, and a partition between said air inlet chamber and said mixing chamber limiting movement of the piston.

6. In a carburetor, the combination of a casing,

a rotatably mounted member mounted in said casing and having its outer surface formed with a venturi formed recess and a vane extending from said member and working in said casing adjacent the outer side thereof, said vane, member and casing cooperating to form an inlet space and a mixing chamber on opposite sides of said vane and a' Venturi passage of variable opening provided by said recess, said vane being operable to move said members in response to differences in pressure on its opposite sides due directly to differences in pressure between said inlet space and said mixing chamber, a fuel jet having its discharge positioned within said variable opening, and means opposing the opening movement of said member and operable to decrease the size of said opening on a decrease of engine suction.

7. In a carburetor, the combination of a casing, a pair of rotatably mounted members mounted in said casing and operatively connected together to rotate in unison, said members each having a complimentary groove formed therein cooperating to form a variable venturi expanding in volume in the direction of flow, a vane extendingv charge end portion of the fuel jet being positioned into an inlet space and a mixing space with said grooves forming a passage of variable opening between said spaces, said vanes being operable to move said members directly in response to differences in pressure at their opposite sides, means opposing the opening movement of said members and operable to. move the same to decrease the. size of said venturi on a decrease ofengine suction, and a fuel jet having its discharge position within said venturi.

8. In a carburetor having an air inlet chamber, a mixing chamber, and a fuel jet, a variable expanding venturi for regulating the admission of air to said mixing chamber, said venturi embodying a rotatabiy mounted member having its outer periphery formed with a substantially V shaped recess of increasing depth in the direction of flow of fuel and air therethrough and forming a variable opening between the air inlet chamber and the mixing chamber, the discharge end portion of the fuel jet being positioned within said opening, and means operating in said mixing chamber in response to engine suction to turn said member against the flow of fuel and air therethrough to increase the size of said variable opening.

9. In a carburetor having an air inlet chamber, a mixing chamber, and a fuel jet, a variable expanding venturi for regulating the admission of air to said mixing chamber, said venturi embodying a pair of rotatable members positioned adjacent one another and having their outer surfaces formed with registering recesses of gradually increasing size in the direction of flow of fuel and air therethrough forming a variable opening between the air inlet chamber and the mixing chamber, the discharge end portion of the fuel jet being positioned within saidopening, and means operating in said mixing chamber in re sponse to differences in static pressure at opposite sides thereof to turn said rotatable members against the flow of fuel and air therethrough and adjust the size of said variable opening.

10. In a carburetor having an air inlet chamber, a mixing chamber, and a fuel jet, a variable expanding venturi for regulating the admission of air to said mixing chamber, said venturi embodying a pair of rotatable members positioned adjacent one another and having their outer surfaces formed with substantially V shaped reg-'- istering recesses of gradually increasing depth in the'direction of flow of fuel and air therethrough and forming a variable opening between the air inlet chamber and the mixing chamber, the diswithin said opening, and means operating in said mixing chamber responsive to differences in static pressure at opposite sides thereof to turn said rotatable members against the flow of fuel and air therethrough and adjust the size of said variable p ning.

11. In a carburetor, the combination of 8 cas- -ing having an inlet end, and an outlet end connectable with an engine, complementary members in the casing, and having progressively expanding grooves which co-act to form a passage be-' tween the inlet and outlet ends variable in area by movement of the members, the direction of expansion of said grooves being such that the area of the passage is increased by movement of the adjacent portions of the members toward the inlet end whereby their movement is opposite to the direction of air flowing through the passage, and means connected with the members and responsive to a difference instatic pressure atthe outlet and inlet ends of the casing produced by engine suction to move the members. 12. In a carburetor having a Venturi chamber, complementary members rotatable about parallel axes and provided with progressively expanding registering grooves to form a Venturi of variable area depending upon the position of rotation of the members, and extensions on said members projecting farther from the axes about which they rotate than all other portions thereof and lying adjacent the walls of .the venturi chamber to be responsive to diflerence' in static pressure at opposite sides of the Venturi forming'members to cause the same to rotate and adjust the area of the venturi;

13. In a carburetor, the combination of a casing having an inlet end and an outlet end connectable with an engine, complementary Venturi-forming members in the casing, means mounting the complementary venturi-forming 5 members for rotation about parallel axes, said members having portions concentric to the axes about which they are rotatable and said conoentric portions having rolling engagement with each other, an extension on one of the members projecting farther from the axis about which it is rotatable than the concentric portion thereof, said extension being responsive to a difference in static pressure at the outlet and inlet ends of the easing produced by engine suction to rotate the 1 5 members, and means connecting the members for simultaneous rotation.

14. In a carburetor, a rotatable member having a tapered throat disposed around its center of rotation and forming a venturi passage, and a. vane substantially diametrically opposite said tapered throat responsive to pressure changes at opposite sides thereof to adjust the member and consequently the tapered throat forming the venturi 15. In a carburetor, a rotatable member having a tapered throat disposed around to its center of rotation and forming a Vepturipassage, said throat cooperating with an element to form an air passage variable in area by movement of the member about its center of rotation, and a vane. substantially diametrically opposite the tapered throat forming the venturi passage and responsive -topressure differences at opposite sides thereof to adjust the member about its center -of rotation and vary the passage afforded by its tapered throat.

. 16. In a carburetor, the combination with a casing having an inlet end and an outlet end connectable with an engine, complementary members in the casing and having progressively expanding grooves which co-act to form a passage between the inlet and outlet ends variable. in area by movement of the members, the direction of expansion of the grooves being such that the area of the passage is increased by movement of the adjacent portions of the members toward the inlet end whereby movement of the said adjacent portions of the members is opposite to the direction of air flowing through the passage, and fluid actuated means connected with the .complementary members and responsive to a difference in static pressure at the outlet and inlet ends of the casing produced by engine suction to move the members.

17. In a carburetor, a carbureting chamber through which air is adapted to flow in response to suction produced in the intake manifold, a venturi tube havingtwo parts relatively rotatable to occupy one extreme position in which the eflective cross sectional area of the tube is reduced and another extreme position in which said area is enlarged, means tending to rotate said parts to the first extreme position, and means responsive to suction produced outwardly of the venturi for rotating said parts to the other extreme position and to intermediate positions.

18. In a carburetor, a carbureting chamber through which air is adapted to flow in response to suction produced in the intake manifold, a Venturi tube having two parts relatively rotatable to occupy one extreme position in which the effective cross sectional area of the tube is reduced and another extreme position in which said area is enlarged, means tending to rotate 'said parts to the first extreme position, and means responsive to suction produced in the intake manifold for rotating said parts to the other extreme position and to intermediate positions.

19. In a carburetor, the combination of a casing having an inlet end, and an outlet end connectable' with an engine, complementary members in the casing co-acting to form a passage between the inlet and outlet ends variable in area by movement of the members, and means connected with the members to co-act therewith and divide the casing into spaced chambers, each opening to one end of the casing and said means being responsive to a difference in static pressure in the spaced chambers of the casing produced by engine suction to move the members.

20. In a carburetor, having an inlet end portion and an outlet end portion connectable with an internal combustion engine, complementary members coacting to form a venturi of variable area, and piston means cooperating with the complementary members to close oif the inlet end portion from the outlet end portion-except for the Venturi opening, and said piston means being connected to the complementary members for moving them to adjust the area of the venturi in accordance with a difference in static pressure at the inlet and outlet end portions of the carburetor.

WERNER. E. ARM$TRONG. 

